Field of the Invention
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The present invention relates to telecommunication
networks, in particular to public telecommunications networks, wherein
telecommunication services are provided to a plurality of subscribers or
users of a telecommunications network.
Background of the Invention
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Telecommunication networks, such as the Public Switched
Telephone Network (PSTN), the Integrated Services Digital Network (ISDN)
or the so-called Virtual Private Networks (VPN) are designed to provide
a certain Grade Of Service (GOS) in terms of a blocking probability. That
is, the probability that a subscriber meets congestion in the network,
such that a call can not be established.
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In order to guarantee a certain GOS, telecommunication
networks have been designed for predetermined blocking percentages, for
example 1% during the "busy hour".
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With the increase of telecommunications traffic and
services, such as calls from the PSTN to mobile networks operating under
the Global System for Mobile communications (GSM), for example, fax and
data transmissions, and the Internet, the traffic load profile of the Plain
Old Telephone System (POTS) has changed over time.
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In order to maintain a particular GOS, a POTS network
operator has to increase network resources to cope with the increase in
telecommunications traffic. On the other hand, during off-busy hour the
network is scarcely loaded, leading to a none-productive over-capacity
in the telecommunications network.
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It is both in the interest of a network operator as
well as the subscribers of a telecommunications network, to find an optimum
between the GOS provided and the network resources required.
Summary of the Invention
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It is an object of the present invention to optimise
the relation between Quality Of Service (QOS) and network resources in
a telecommunications network.
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This and other objects and advantages are provided by
the present invention in a method of controlling access to a telecommunications
network, wherein subscribers of the telecommunications network are
provided with a network quality access right, and access to the network
is controlled from actual network quality of service by comparing the
network quality access right against the actual network quality of service.
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The method according to the invention introduces a
network quality access right, by which subscribers are able to select a
QOS, different from the nominal QOS which is aimed at by the network
operator. That is, a subscriber may avail himself of a lower QOS, for
example less transmission capacity or reduced transmission bandwidth, in
order to be able to establish a call even during network congestion, in
order to avoid as much as possible call blocking.
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The network quality access right provided may relate
to several QOS issues in a telecommunications network including, but not
limited to network congestion, reduced transmission capacity, reduced level
of additional services involving scarce network resources such as Call
Forwarding on Busy (CFB), use of network mailbox services and the like.
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On the other hand, the network operator, with the
network quality access right according to the present invention, receives
a tool for dimensioning the telecommunications network such to reduce the
unproductive network over-capacity.
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In a further embodiment of the method according to the
invention, levels and/or types of network quality and network quality
access right have been defined, and wherein access to the telecommunications
network is controlled if the actual network quality level is below
a network quality access right level provided to a subscriber.
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In the method according to the invention, the actual
network quality level can be continuously calculated from network load
measurements, for example. Network load measurement is a technique familiar
to those skilled in the art.
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In a preferred embodiment of the method according to
the invention, the actual network quality level is calculated as a
congestion probability level. That is, the probability of not being able
to provide the nominal quality of service of the network. Such a congestion
probability level can be calculated from the actual traffic or network
load and historical traffic information, such as busy-hour, pre- and post
busy hour traffic etc.
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In order to reduce processing capacity, in a yet further
embodiment of the method according to the invention, control of the access
to a telecommunications network is initiated if the actual network quality
drops below a predetermined level.
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With the method according to the invention, it is
feasible not only to control access to the network at call set-up but also
during a call in progress, eventually resulting in termination of the call
by the network to free network resources for subscribers requiring a higher
level of network quality or even the nominal network quality.
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In case of a termination, the method according to the
invention provides a suitable signalling, such as an announcement that
the call will be terminated from a certain point in time, for example.
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To avoid termination or blocking of calls for lifeline
purposes, i.e. police, fire brigades, ambulance etc., the method according
to the invention is correspondingly arranged. Further, it can be provided
to place calls of this type, regardless a particular network quality access
right allocated to a subscriber or network terminal.
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The network quality access right according to the
invention can be allocated by a network operator and maintained thereby,
or by a subscriber. For example, by preceeding a call by suitable
signalling, such as a prefix, to be dialled or keyed in by the subscriber
at call set-up.
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In order to stimulate subscribers of using the network
quality access right feature according to the present invention, network
operators may offer reduced call charges in return to a particular network
quality access right level, for example. Further network operators may
offer lower subscription fees to subscribers to which a particular network
quality access right is provided on a permanent basis.
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The invention further relates to a telecommunications
network, comprising telecommunication equipment for establishing calls
between subscribers of the network, comprising network quality measuring
means for measuring the actual network quality, means for allocating
network quality access rights to subscribers of the network, means for
evaluating the actual network quality against the network quality access
rights, and means for controlling access to the network by subscribers
and coupled to the evaluating means.
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In a yet further embodiment of the system according
to the invention, the network quality access right may not only be
available in or from the network, but also from subscriber equipment
connected to the network. That is, stored in the subscriber equipment or
signalled therefrom at call set-up, such as a prefix disclosed above.
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The above-mentioned and other features and advantages
of the invention are, for a better understanding thereof, described in
more detail in the following description with reference to the enclosed
drawings.
Brief Description of the Drawings
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- Figure 1 shows, for illustrative purposes, a graph of
the number of calls in a telephone network versus the time of the day.
- Figure 2 shows a simplified block diagram of a
telecommunications system, incorporating the present invention.
- Figure 3 shows a simplified flowchart diagram of an
embodiment of the method according to the present invention.
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Detailed Description of the Embodiments
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Figure 1 shows, for illustrative purposes, a graph 1
of the number of calls in a telecommunications network, such as the Public
Switch Telephone Network (PSTN) versus the time of the day. Due to its
illustrative nature, no explicit quantities are indicated.
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Line 2 corresponds to a number of calls in the network,
for which a predetermined or specified blocking percentage applies. Above
this level, subscribers meet congestion. That is, the probability that
a call can not be placed is above the designed or nominal value.
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The vertical distance between the line 2 and the graph
1 is a measure of the spare network capacity or over-capacity, required
for providing a desired Grade Of Service (GOS).
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The Quality Of Service (QOS) provided to a subscriber
by the network, is strongly related to the actual load of the network.
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The QOS provided by a telecommunications network, as
experienced by subscribers thereof, can be expressed not only in terms
of call blocking percentages, but also with regard to the transmission
capacity offered, i.e. the communication channel bandwidth or bit rate,
call set-up time, the performance of call services provided by the network
etc.
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With the network quality access right according to the
invention, the number of calls, the transmission capacity provided, the
call services to be executed etc., can be controlled for individual
subscribers or groups of subscribers of the network. This can be
illustrated in an example with respect to figure 1.
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Assume a subscriber is provided with a network quality
access right corresponding to a QOS level below a designed or specified
network quality level, for example. In figure 1 this can be illustrated
by a line 3 below the line 2.
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For subscribers having a network quality access right
corresponding to line 3, if the load of the network is above the quantity
corresponding to line 3, access to the network is provided in accordance
with the particular network quality access right.
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Network access control may range from blocking of the
special network services, such as Call Forwarding (CF), reduced
transmission or communication channel bandwidth, reduced data bit rates,
increased call set-up times etc., and eventually complete blocking of the
access to the network.
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With regard to the latter, exemptions can be made for
lifeline calls to the police station, the fire brigade, an ambulance or
other emergency services, for example.
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Those skilled in the art will appreciate that, if for
particular subscribers access to the network is controlled, the QOS
provided to subscribers without network quality access rights or network
quality access rights corresponding to a more advanced level, will
generally benefit. These subscribers can be better serviced, compared to
a network without quality access control. In particular, during the time
of the day wherein the demand on the network is very high, such as at busy-hour
corresponding to the peak values 4, 5 and 6 of graph 1.
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On the other hand, a subscriber having a network quality
access right including less transmission bandwidth, for example, may
benefit in that also during busy-hour still a call can be placed, i.e.
access to the network is provided, however with less quality.
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The network operator benefits from quality access right
control in that the overall network spare capacity can be reduced, or,
with the same amount of resources, for selected subscribers, the specified
or nominal QOS can be provided without direct further investments in
network equipment.
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The network operator may offer benefits like reduced
subscription fees and/or reduced call charging rates to those subscribers
accepting a less QOS, for example.
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Figure 2 shows a typical Intelligent Network (IN)
telecommunications system 10, illustrative for a PSTN. Subscribers or users
11, 12, 13 connect by a subscriber or drop line 14 to a Local Exchange
(LE) 15, 16, 17, respectively. The LE 15, 16, 17 connect by trunk lines
20 to a Trunk Exchange (TE) 18, 19, as shown. The TE 18, 19 connect by
a trunk line 21.
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Following modern IN-switching equipment, the TE 18,
19 are of the type comprising Service Switching Point (SSP) equipment 25,
26, respectively. The SSP 25, 26 control the associated TE 18, 19 in order
to establish the required transmission channels for exchanging calls by
the subscribers 11, 12, 13.
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To each of the SSP 25, 26 Service Control Point (SCP)
equipment associates, i.e. SCP 27, 28, respectively. The SCP operate for
controlling telecommunication network services offered to the subscribers.
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For signalling purposes, a signalling network is
provided, schematically indicated by signalling links 22, 23, 24 between
the SCP and SSP. The signalling network, although not explicitly
illustrated, operates down to the subscribers 11, 12, 13 via the trunk
and drop lines.
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In an IN-network 10 shown, the method according to the
invention can be implemented in the SCP equipment 27, 28, as generally
indicated by blocks 29.
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The blocks 29 are operative to measure and calculate
actual network quality levels; to allocate network quality access rights
to subscribers and/or to calls from subscribers; to evaluate network access
quality rights against actual network quality levels; and to control access
to the network of subscribers c.q. calls, in accordance with the applicable
quality access rights and actual network quality of service.
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Those skilled in the art will appreciate that the
operation of the blocks 29, as disclosed above, can be implemented by
software and hardware components and using the resources already available
in modern SCP.
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Those skilled in the art will appreciate that call load
measurements may also be provided in the SSP 25, 26 and/or the LE 15, 16,
17.
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Call charging or subscription incentives to users
accepting a certain level of network quality access right associated with
a service quality less than for which the network has been specified or
designed, can be exchanged between SCP 27, 28 and SSP 25, 26 through the
signalling network 22, 23, 24 following established rules and procedures.
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Network quality access right information, in accordance
with the invention, may also be stored in the equipment of the subscribers
11, 12, 13 which, for this purpose, have to be provided with suitable
storage and retrieval means, as indicated by blocks 30.
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An embodiment of the method according to the invention
is now illustrated in connection with figure 3, which shows a flowchart
diagram. Normal flow is assumed from the top of the chart to the bottom
thereof.
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Block 31 discloses continuously monitoring of the
quality of service of the network. Monitoring can be based on several
network parameters, among which actual call load, call set-up times, call
blocking, historical traffic data etc.
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Block 32 assumes call set-up by a subscriber, such as
the subscribers 11, 12, 13 in figure 2.
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Block 33 is a decision block, in which is tested whether
the call has to be processed in accordance with a particular network
quality access right. A network quality access right can be retrieved from
an inquiry of the SCP to which the subscriber is allocated, that is system
block 29 thereof. A quality of service access right may also be signalled
from the subscriber at call set-up 32. This, for example, in that the
subscriber has dialled or keyed in a particular prefix before the
subscriber number of the called party or other suitable signalling, such
as special function keys and the like.
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In the absence of a quality of service access right
the call will be processed following established call set-up procedures,
indicated by block 34, i.e. corresponding to decision "no" of block 33.
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However, in the case of call set-up following a network
quality access right, i.e. decision "yes" of block 33, the call will be
processed in accordance with the particular network quality access right,
as shown by block 35.
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Decision block 36 tests whether the call has been set-up.
If "yes", it is tested by block 38, whether the network quality access
right meets the actual network quality monitored by block 37. If not, i.e.
decision "no", the call is terminated. That is, if the actual network
quality level drops below the level corresponding to the network quality
access right of the subscriber, the call will be terminated.
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Termination of a call can be preceeded by proper
announcements or other suitable signalling. Special calls, like calls to
emergency services, may not be terminated or restricted to network control
access, such as to be incorporated in the system block 29, for example.
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Instead of termination of the call, same may be further
processed in accordance with an applicable network quality access right,
for example.
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The invention is not limited or restricted to the
embodiments described and shown in a PSTN. The invention may also be
applied to a Virtual Private Network (VPN), for example. Various
modifications and additions can be made within the scope of the invention
as defined in the attached claims.
